I've been playing around with VMWare and vitalization for a while now and I have to say I really like it. I have a virtual Ubuntu image that I am using to learn Ruby on Rails with. I installed VMWare's server on my file server so I can run VM's from any PC in my house.
So last night I was working on my gateway PC when the thought hit me: Why not create my own virtual domain? I could create an image and install IPCop on it, add three virtual Ethernet cards to the VM and bridge the fourth to a real NIC and viola - Instant Domain. Just add more servers.
From there I could add servers to the Green, Orange and Blue Virtual zones and just play around with configurations. I could create a mini-web farm, play around with MySQL replication, a virtual cluster, anything.
Granted I would bump into a Hardware wall pretty quick, I dumped all my old PC's so now I don't have that many to play with. But I bet I could still but together something pretty cool.